Liquid fuels for reaction motors



United States Pat o 2,947,618 LIQUID FUELS FOR REACTION MoroRs Leonard A. Stengel and Emory E. Toops, in, Terre Haute, Ind., assignors to Commercial Solvents Corporation, New York, N.Y., a corporation of Maryland No Drawing. Filed Jan. 14, 1959, Ser. No. 786,678

2 Claims. (Cl. 52-.5)

Our invention relates to new liquid fuels for reaction motors, and more particularly, to improved methanol base fuels of improved power suitable for use in all types of fuel injection engines.

Our improved fuels, while suit-able for use in all types of fuel injection engines, are particularly adaptable not only to piston-type internal combustion engines, but also to all engines which function on the jet principle such as pulse, turbo and ramjets and turboprops. The advent of aircraft of greatly increased load capacity has greatly increased the problems of getting the aircraft airborne within the limitations of the spaces normally available. This is particularly the case with the most recent jet airliners which require 10,000 feet of runway to take off on a hot day when fully loaded. Similar problems are involved in getting both fast fighter planes and heavily loaded bomber planes airborne from the limited space of aircraft carriers. Our improved fuels are especially useful in all such cases.

The basis of our improved fuels is methanol to whichis added an ingredient to give added thrust and other useful properties without at the same time detracting from the other advantages in the use of methanol as a fuel for injection engines. Methanol has beenused previously either alone or mixed with water, in fuel injection engines, primarily to lower combustion temperatures and to provide added power. The flame temperature of methanol in air, for example, is about 200 'F. below that of conventional hydrocarbon fuels. This would be expected from the fact that the B.t.u. value of methanol per pound is 8,510 as compared to 19,171 for pentane, a hydrocarbon standard. Fuels are normally rated by their B.t.u. content per pound but during take-off of an airplane, the maximum power or thrust is limited by the maximum amount of air available for combustion. For this reason, during takeoff, or for very high altitude flying, fuels are more correctly rated in the terms of \B.t.u.s per pound of air.

The combination of nitromethane with methanol has previously been suggested. While such combinations give added power from fuel injection engines, such combinations have never found large commercial uses because of the relatively high cost of such compositions and also because of the fact that nitromethane has not been available commercially in large quantities.

We have now discovered that monomethylamine nitrate can be dissolved in methanol up to about 45% by weight at 70-75 F. At reduced temperatures, smaller amounts of monomethylamine nitrate are soluble in the methanol, the amount depending upon the temperature. For example, at 5 F., 17.5% monomethylamine by weight is soluble in methanol. We have found that monomethylamine nitrate in amounts as low as about 5% provides added thrust for take-01f or for other periods when added thrust is needed from jet-type engines. Generally, we prefer to utilize from about 5 to about 20% by weight monomethylamine nitrate in our fuel mixture for most purposes.

, 2,947,618 Patente d Aug. 2,

Our fuels can be prepared by adding the monomethylamine nitrate, with stirring, to warm methanol solutions, about'50 C., until the desired composition is obtained: The fuel compositions. prepared as above described have, in general, vapor pressures ranging between the vapor pressures of pure methanol and, for reference purposes, pure pentane, and having freezing points ranging from slightly above 0 F. to approximately -71" F., they are in general usable under the same'conditions and in the same types of engines as those in which methanol and pentane are used. I 7

When our improved alcohol base fuel compositions are used in air-breathing engines, such as turbojet engines, ramjet engines, diesel engines, etc., principles of operation which apply are similar to those applicable to present day enginesemploying ordinary hydrocarbonor alcohol fuels. In all of these engines the oxygen in the air is mixed with the fuel so that the fuel-air ratio is approximately stoichiometric. In this way, complete burning and efiicient operation are assured. For example, when an by weight methanol and 20% monomethylamine nitrate mixture is used as a turbojet engine fuel, a weight ratio of air to fuel of at least about 5.5:1 is desired. After combustion of our fuels in the cornbustion chambers of a turbojet engine, additional air is bled into the exhaust gases prior to passing them through the gas turbine blades in order that the turbine blades may be maintained at a temperature of about 1500- 1600 F. v

To utilize the compositions of our invention, we merely flow them, at a desired rate, into a combustion chamber containing a suitable heating element, such as a white hot platinum grid or glow plug to initiate combustion. Once combustion has begun, the heating element can be removed or may remain within the reaction motor to catalyze the burning rate of the fuel.

The following table shows physical properties for a number of our compositions prepared as above described:

=TABLE Properties of methylamine nitrate-methanol jet fuels The following examples more fully illustrate how our invention is used in various types of motors, but it is not intended that our invention be limited to the motors, specific fuels, or processes described.

EXAMPLE I To test our fuel in a turbojet engine, 200 pounds of methylamine nitrate was mixed with 800 pounds of methanol at 50 C. to form a high density methanol solution. This fuel was then metered. into the combustors of a I-35 axial flow turbojet engine through the fuel nozzles. The fuel was metered :into the combustors at a rate such that the air-fuel ratio was about 5.5 :1. At this air-fuel ratio, the mixture burned well and increased thrust noticeably over the use of methanol alone in a similar experiment.

EXAMPLE II In a further experiment, a fuel mixture similar to the mixture of Example I was passed into an afterburner section of a turbojet engine with the same noticeable increase in thrust.

EXAMPLE III A solution of methanol and 10% by weight monomethylamine nitrate was fed into a small thrust chamber made up of available 1" stainless steel pipe and stainless steel pipe fittings. The fuel injection nozzle was made up from a pipe plug. An orifice diameter of 01040" was drilled in the pipe plug and a needle valve assembly was seated in and welded onto the lug- For ease of repair, a 1" union was used to attach the nozzle to the. 4" pipe which comprised the burning chamber. An oxygen inlet tube anda bourdon-type pressure gauge with a range of 600 p.s.i. were attached to the burning chamber through the plug. A reducing coupling was utilized as the motor nozzle. The above-described fuel and an approximately stoichiometric amount of gaseous oxygen were introduced into the thmst chamber through the injection nozzle. Ignition was initiated by preheating the chamber to a red heat. The fuel burned well with good thrust.

Now having described our invention what we claim is:

1. A liquid fuel for combustion engines consisting essentially of from about 55 to about 95% by weight methanol and from about 5 to about by weight monomethylamine nitrate.

2. A liquid fuel for combustion engines consisting essentially of from about to about by weight methanol and from about 5 to about 20% by weight monomethylamine nitrate.

References Cited in the file of this patent UNITED STATES PATENTS 2,455,205 Whetstone et al. Nov. 30, 1948 2,662,817 Russell et a1. Dec. 15, 1953 2,847,292 Hager et a1. Aug. 12, 1958 FOREIGN PATENTS 815,880 France July 24, 1937 OTHER REFERENCES Le Roux: Mem. Poudres, vol. 34, 1952, pages 129-146. 

1. A LIQUID FUEL FOR COMBUSTION ENGINES CONSISTING ESSENTIALLY OF FROM ABOUT 55 TO ABOUT 95% BY WEIGHT METHANOL AND FROM ABOUT 5 TO ABOUT 45% BY WEIGHT MONOMETHYLAMINE NITRATE. 